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Date:      Mon, 3 Mar 2008 21:27:15 +0300
From:      pluknet <pluknet@gmail.com>
To:        "Kostik Belousov" <kostikbel@gmail.com>
Cc:        FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: panic: mutex Giant owned at nfs_syscalls.c:556
Message-ID:  <a31046fc0803031027y6b126b9alb6899e470c8e109c@mail.gmail.com>
In-Reply-To: <20080303164353.GW57756@deviant.kiev.zoral.com.ua>
References:  <a31046fc0802200328i31833093i15ac0db5e764b40a@mail.gmail.com> <a31046fc0803021841k752ac5afx8ccd7d08784da713@mail.gmail.com> <20080303133406.GV57756@deviant.kiev.zoral.com.ua> <a31046fc0803030814v53b80b0ey6808b0aacf4e028e@mail.gmail.com> <20080303164353.GW57756@deviant.kiev.zoral.com.ua>

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On 03/03/2008, Kostik Belousov <kostikbel@gmail.com> wrote:
[snip]
>  To summarize, I need both the tcpdump and kernel/witness messages from
>  the panic.
>

I'm sorry. Here it is.
http://pluknet.nm.ru/dev/tcpdump-nfsserver-full.raw

The messages (same as unread msgbuf in initial posting, hand-scribed):
panic: mutex Giant owned at
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_syscalls.c:556
KDB: enter: panic
[thread pid 601 tid 100055 ]
Stopped at kdb_enter+0x3a: movl $0,kdb_why
db> show locks
exclusive sleep mutex nfsd_mtx r = 0 (0xc2e0af40) locked @
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_syscalls.c:501
exclusive sleep mutex Giant r = 0 (0xc07e6410) locked @
/usr/src/sys/kern/vfs_lookup.c:663

>  Nevertheless, the patch below might help with the panic during
>  the unlinking (not tested).
>
>  diff --git a/sys/nfsserver/nfs_serv.c b/sys/nfsserver/nfs_serv.c
>  index 446651d..87e1aaa 100644
>  --- a/sys/nfsserver/nfs_serv.c
>  +++ b/sys/nfsserver/nfs_serv.c
>  @@ -2146,7 +2146,7 @@ nfsrv_remove(struct nfsrv_descript *nfsd, struct nfssvc_sock *slp,
>         nfsfh_t nfh;
>         fhandle_t *fhp;
>         struct mount *mp = NULL;
>  -       int vfslocked;
>  +       int vfslocked, vfslocked1;
>
>         nfsdbprintf(("%s %d\n", __FILE__, __LINE__));
>         ndclear(&nd);
>  @@ -2168,7 +2168,11 @@ nfsrv_remove(struct nfsrv_descript *nfsd, struct nfssvc_sock *slp,
>         nd.ni_cnd.cn_flags = LOCKPARENT | LOCKLEAF | MPSAFE;
>         error = nfs_namei(&nd, fhp, len, slp, nam, &md, &dpos,
>                 &dirp, v3,  &dirfor, &dirfor_ret, td, FALSE);
>  -       vfslocked = NDHASGIANT(&nd);
>  +       vfslocked1 = NDHASGIANT(&nd);
>  +       if (vfslocked && vfslocked1)
>  +               VFS_UNLOCK_GIANT(vfslocked1);
>  +       if (vfslocked || vfslocked1)
>  +               vfslocked = 1;
>         if (dirp && !v3) {
>                 vrele(dirp);
>                 dirp = NULL;
>
>

Now the last lock triplex looks like:
vfslocked lock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c, 2161
vfslocked lock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_srvsubs.c, 1106
vfslocked lock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_srvsubs.c, 673
vfslocked unlock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_srvsubs.c, 916
vfslocked1 unlock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c, 2173
^^^
vfslocked unlock in
/usr/src/sys/modules/nfsserver/../../nfsserver/nfs_serv.c, 2238

And no panic. Thanks.

wbr,
pluknet



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